Panel fastener

ABSTRACT

A fastener for attachment to a panel, having an inner skin and an outer skin, via a panel aperture in the outer skin. The fastener including an insert pillar, a base plate, a spring, and a top insert arranged and configured to allow longitudinal compression of the spring resulting in movement and deflection of components to promote ease of use, security, and durability.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentapplication Ser. No. 63/230,102, filed on Aug. 6, 2021, all of which isincorporated by reference as if completely written herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to panel fasteners.

BACKGROUND OF THE INVENTION

Honeycomb cored sandwich panels are commonly used in a multitude ofapplications because they offer the advantages of being high strength,inherently rigid, and a reduction of weight. Furthermore, honeycombcored sandwich panels have highly effective thermal and acousticalinsulating properties. In order for honeycomb cored sandwich panels tobe useful they require structural load attachment points. Generallyhoneycomb cored sandwich panels cannot carry concentrated unit loadingwell. Early techniques for mounting panels included solid sectionalfillers such as voids filled with epoxy or wooden blocks placed in thepanels during the manufacturing process in order to form mountingpoints. These techniques have severe shortcomings, such as being heavy,difficult to implement, non-customizability, and also required theremoval of sufficient core honeycomb material which results in aweakened panel.

Later other fasteners were created to overcome the issues previouslymentioned. One embodiment of fastener required a panel aperture to bebored through one of the panel's skins and honeycomb core. Next, epoxywas then injected into the void and a threaded insert is pressed intoplace. This embodiment of panel fastener had the disadvantages of beingheavy, which negated some of the benefits of using a honeycomb coredpanel, and required the fastener insert to be held in place until theepoxy set up. In another embodiment, a mechanical fastener requires apanel aperture to be bored through one of the panel's skins and thehoneycomb core. The other panel's skin would have a smaller panelaperture bored into it. An insert is then placed into the original panelaperture, and a smaller secondary insert with a conical flange is placedin the second panel aperture. The smaller secondary insert has threadsthat engage with threads located in the bore of the first insert. As thetwo inserts are rotated the inserts draw together and deform the secondpanel skin to match the conical flange. Such designs also have the drawbacks of being heavy, and also require special training to properlyinstall.

BRIEF DESCRIPTION OF THE DRAWINGS

Without limiting the scope of the present invention as claimed below andreferring now to the drawings and figures:

FIG. 1 is an isometric view of an embodiment of a panel fastenerinstalled in a honeycomb panel;

FIG. 2 is a cross-section view of an embodiment of a panel fastenerinstalled in a honeycomb panel;

FIG. 3 is an isometric view of an embodiment of an insert pillar;

FIG. 4 is a top plan view of an embodiment of an insert pillar;

FIG. 5A is a side elevation view of an embodiment of an insert pillar;

FIG. 5B is another side elevation view of an embodiment of an insertpillar;

FIG. 6 is a bottom plan view of an embodiment of an insert pillar;

FIG. 7 is an isometric view of an embodiment of a clip;

FIG. 8 is a top plan view of an embodiment of a clip;

FIG. 9 is an isometric view of an embodiment of a base plate;

FIG. 11 is a top plan view of an embodiment of a base plate;

FIG. 12 is a bottom plan view of an embodiment of a base plate;

FIG. 13 is a bottom plan view of an embodiment of a base plate with aninstalled pillar;

FIG. 14 is a top plan view of an embodiment of a base plate with aninstalled pillar and clip;

FIG. 15 is an isometric view of an embodiment of a support ring;

FIG. 16 is a top plan view of an embodiment of a support ring;

FIG. 17 is a bottom plan view of an embodiment of a support ring;

FIG. 18 is side elevation view of a support ring;

FIG. 19 is an isometric view of an embodiment of a pillar, clip, baseplate and support ring;

FIG. 20 is a side elevation view of an embodiment of a pillar, clip,base plate and support ring;

FIG. 21 is a top plan view of an embodiment of a pillar, clip, baseplate and support ring;

FIG. 22 is a side elevation view of a spring;

FIG. 23 is a top plan elevation view of a spring;

FIG. 24 is an isometric view of an embodiment of a pillar, clip, baseplate and spring;

FIG. 25 is an isometric view of an embodiment of a pillar, clip, baseplate, support ring and spring;

FIG. 26 is a top plan view of an embodiment of a pillar, clip, baseplate, support ring and spring;

FIG. 27 is an isometric view of an embodiment of a prong ring;

FIG. 28 is a top plan view of an embodiment of a prong ring;

FIG. 29 is a bottom plan view of an embodiment of a prong ring;

FIG. 30 is a side elevation view of an embodiment of a prong ring;

FIG. 31 is an isometric view of an embodiment of a base plate, supportring and prong ring;

FIG. 32 is an isometric view of an embodiment of a pillar, clip, baseplate, support ring, spring and prong ring;

FIG. 33 is a top plan view of an embodiment of a pillar, clip, baseplate, support ring, spring and prong ring;

FIG. 34 is an isometric view of an embodiment of a retainer latch;

FIG. 35 is a top plan view of an embodiment of a retainer latch;

FIG. 36 is a side elevation view of an embodiment of a retainer latch;

FIG. 37 is an isometric view of an embodiment of a pillar, clip, baseplate, support ring, spring, prong ring and retainer latch;

FIG. 38 is a top plan view of an embodiment of a pillar, clip, baseplate, support ring, spring, prong ring and retainer latch;

FIG. 39 is an isometric view of an embodiment of a top insert;

FIG. 40 is a top plan view of an embodiment of a top insert;

FIG. 41 is a bottom plan view of an embodiment of a top insert;

FIG. 42 is a side elevation view of an embodiment of a top insert;

FIG. 43 is an isometric view of an embodiment showing a pillar, clip,prong ring, retainer latch and top insert; and

FIG. 44 is a top plan view of an embodiment showing a base plate,support ring, prong ring, retainer latch and top insert.

FIG. 45 is an isometric view of an embodiment of a panel fastenerinstalled in a honeycomb panel;

FIG. 46 is a cross-section view of an embodiment of a panel fastenerinstalled in a honeycomb panel;

FIG. 47 is an exploded isometric view of an embodiment of panelfastener;

FIG. 48 is an isometric view of an embodiment of an insert pillar;

FIG. 49 is a top plan view of an embodiment of an insert pillar;

FIG. 50A is a side elevation view of an embodiment of an insert pillar;

FIG. 50B is another side elevation view of an embodiment of an insertpillar;

FIG. 51 is a bottom plan view of an embodiment of an insert pillar;

FIG. 52 is an isometric view of an embodiment of a base plate;

FIG. 53 is a side elevation view of an embodiment of a base plate;

FIG. 54 is a top plan view of an embodiment of a base plate;

FIG. 55 is a bottom plan view of an embodiment of a base plate;

FIG. 56 is an isometric view of an embodiment of a base plate with aninstalled pillar;

FIG. 57 is a top plan view of an embodiment of a base plate with aninstalled pillar;

FIG. 58 is a bottom plan view of an embodiment of a base plate with aninstalled pillar;

FIG. 59 is an isometric view of an embodiment of a base platefoundation;

FIG. 60 is a top plan view of an embodiment of a base plate foundation;

FIG. 61 is a side elevation view of an embodiment of a base platefoundation;

FIG. 62 is an isometric view of an embodiment of a spring;

FIG. 63 is a side elevation view of a spring;

FIG. 64 is a top plan elevation view of a spring;

FIG. 65 is a bottom plan elevation view of a spring;

FIG. 66 is an isometric view of an embodiment of a pillar, base plate,base plate foundation and spring;

FIG. 67 is an isometric view of an embodiment of a top insert;

FIG. 68 is a side elevation view of an embodiment of a top insert;

FIG. 69 is a top plan view of an embodiment of a top insert;

FIG. 70 is a bottom plan view of an embodiment of a top insert;

FIG. 71 is an isometric view of an embodiment of a base plate, baseplate foundation, spring, and top insert;

FIG. 72 is an isometric view of an embodiment of a panel fastenerinstalled in a honeycomb panel;

FIG. 73 is a cross-section view of an embodiment of a panel fastenerinstalled in a honeycomb panel;

FIG. 74 is an exploded isometric view of an embodiment of panelfastener;

FIG. 75 is an isometric view of an embodiment of an insert pillar;

FIG. 76 is a top plan view of an embodiment of an insert pillar;

FIG. 77A is a side elevation view of an embodiment of an insert pillar;

FIG. 77B is another side elevation view of an embodiment of an insertpillar;

FIG. 78 is a bottom plan view of an embodiment of an insert pillar;

FIG. 79 is an isometric view of an embodiment of a base plate;

FIG. 80 is a side elevation view of an embodiment of a base plate;

FIG. 81 is a top plan view of an embodiment of a base plate;

FIG. 82 is a bottom plan view of an embodiment of a base plate;

FIG. 83 is an isometric view of an embodiment of a base plate with aninstalled pillar;

FIG. 84 is a top plan view of an embodiment of a base plate with aninstalled pillar;

FIG. 85 is a bottom plan view of an embodiment of a base plate with aninstalled pillar;

FIG. 86 is an isometric view of an embodiment of a base platefoundation;

FIG. 87 is a top plan view of an embodiment of a base plate foundation;

FIG. 88 is a side elevation view of an embodiment of a base platefoundation;

FIG. 89 is an isometric view of an embodiment of a spring;

FIG. 90 is a side elevation view of a spring;

FIG. 91 is a top plan elevation view of a spring;

FIG. 92 is a bottom plan elevation view of a spring;

FIG. 93 is an isometric view of an embodiment of a pillar, base plate,base plate foundation and spring;

FIG. 94 is an isometric view of an embodiment of a top insert;

FIG. 95 is a side elevation view of an embodiment of a top insert;

FIG. 96 is a top plan view of an embodiment of a top insert;

FIG. 97 is a bottom plan view of an embodiment of a top insert;

FIG. 98 is an isometric view of an embodiment of a pillar, base plate,base plate foundation, spring, and top insert;

FIG. 99 is an isometric cross-section view of an embodiment of a panelfastener in a pre-installed state within a honeycomb panel, having ahelical coil insert;

FIG. 100 is another isometric cross-section view of an embodiment of apanel fastener in a pre-installed state within a honeycomb panel; and

FIG. 101 is an isometric cross-section view of an embodiment of a panelfastener in an installed state within a honeycomb panel.

These illustrations are provided to assist in the understanding of theexemplary embodiments of panel fasteners as described in more detailbelow and should not be construed as unduly limiting the specification.In particular, the relative spacing, positioning, sizing, and dimensionsof the various elements illustrated in the drawings may not be drawn toscale and may have been exaggerated, reduced, or otherwise modified forthe purpose of improved clarity. Those of ordinary skill in the art willalso appreciate that a range of alternative configurations have beenomitted simply to improve the clarity and reduce the number of drawings.

DETAILED DESCRIPTION OF THE INVENTION

Honeycomb cored sandwich panels are commonly used in a multitude ofapplications because they offer the advantages of being high strength,inherently rigid, and a reduction of weight. Furthermore, honeycombcored sandwich panels have highly effective thermal and acousticalinsulating properties. In order for honeycomb cored sandwich panels tobe useful they require structural load attachment points. Generallyhoneycomb cored sandwich panels cannot carry concentrated unit loadingwell. Early techniques for mounting panels included solid sectionalfillers such as voids filled with epoxy or wooden blocks placed in thepanels during the manufacturing process in order to form mountingpoints. These techniques have severe shortcomings, such as being heavy,difficult to implement, non-customizability, and also required theremoval of sufficient core honeycomb material which results in aweakened panel.

Later other fasteners were created to overcome the issues previouslymentioned. One embodiment of fastener required a panel aperture to bebored through one of the panel's skins and honeycomb core. Next, epoxywas then injected into the void and a threaded insert is pressed intoplace. This embodiment of panel fastener had the disadvantages of beingheavy, which negated some of the benefits of using a honeycomb coredpanel, and required the fastener insert to be held in place until theepoxy set up. In another embodiment, a mechanical fastener requires apanel aperture to be bored through one of the panel's skins and thehoneycomb core. The other panel's skin would have a smaller panelaperture bored into it. An insert is then placed into the original panelaperture, and a smaller secondary insert with a conical flange is placedin the second panel aperture. The smaller secondary insert has threadsthat engage with threads located in the bore of the first insert. As thetwo inserts are rotated the inserts draw together and deform the secondpanel skin to match the conical flange. Such designs also have the drawbacks of being heavy, and also require special training to properlyinstall.

An embodiment of the present invention, as seen in FIG. 1 , is a snap-inhoneycomb panel fastener (100) that has the advantage over the prior artof not only being easy to install, but also limits the amount of weightadded to the panel (P). One major advantage of the current inventionover the prior art, is that the fastener (100) locks into place whenpressed into a panel aperture (PA). In the embodiment illustrated inFIG. 2 , the fastener (100) may include an insert pillar (200), a clip(300), a base plate (400), a support ring (500), seen best in FIGS.15-20 , a spring (600), a prong ring (700), a retainer latch (800), seenbest in FIGS. 34-37 , and/or a top insert (900). Various embodimentswill be disclosed throughout, some of which may contain all of theseelements while others only require a few of these elements.

Generally, the fastener (100) may have a fastener proximal end (110) anda fastener distal end (120), as seen in FIG. 2 . FIG. 1 shows anembodiment in an installed state within a honeycomb panel (P). FIG. 2shows a cross-section of an embodiment in an installed state within ahoneycomb panel (P).

The insert pillar (200), as seen in FIGS. 3-6, and 9 forms the core ofthe fastener (100). The insert pillar (200) may include a pillarproximal end (210), a pillar distal end (220), seen in FIG. 5 a a pillarbore (230) having pillar bore threads (232), seen in FIG. 19 , a pillarbore width (234) and a pillar bore length (236), seen in FIG. 5 a , apillar bore body portion (240), abbreviated PBP throughout, having a PBPwidth (242) and a PBP length (244), seen in FIGS. 3, 5 a, and 5 b, apillar spacing portion (250), abbreviated PSP throughout, seen in FIG. 3, having a PSP width (252) and a PSP length (254), seen in FIGS. 5 a and5 b , a pillar clip receiving portion (260), abbreviated PCRPthroughout, seen in FIG. 3 , having a PCRP width (262) and a PCRP length(264), seen in FIGS. 5 a and 5 b , and a plurality of pillar lobes (270)with each pillar lobes (270) having a pillar lobe first width (272), apillar lobe second width (273), seen in FIG. 4 , a pillar lobe length(274), seen in FIG. 5 a , a pillar lobe first radius (276), and a pillarlobe second radius (278), seen in FIG. 6 . In one embodiment the PSPlength (254) is greater than the PRCP length (264), while in a furtherembodiment the PSP length (254) is at least 50% greater than the PRCPlength (264), and at least 75%, 100%, 150%, and 200% greater inadditional embodiments. A further series of embodiments caps this rangesuch that the PSP length (254) is no more than 10 times the PRCP length(264), and no more than 8 times and 6 times in further embodiments.

The plurality of pillar lobes (270) interact with the base plate (400)to prevent the rotation of the insert pillar (200) with respect to thebase plate (400). Thus, the pillar lobes (270) may be configured in anycomplimentary geometry, however any of the disclosed embodiments providethe benefit of improved stress distribution, ease of manufacturing, andeasy of assembly. The pillar bore length (236) is the distance betweenthe pillar proximal end (210) and the pillar distal end (220), as seenin FIG. 5 a . Additionally, it should be noted that in the illustratedthrough-bore embodiment the pillar bore length (236) is the equivalentof the sum of the PBP length (244), the PSP length (254), the PCRPlength (264) and the pillar lobe length (274), as seen in FIG. 5 a ,however, the pillar bore need not extend all the way from the pillarproximal end (210) to the pillar distal end (220). In one embodiment thepillar lobe length (274) is less than the PSP length (254), and in afurther embodiment the pillar lobe length (274) is greater than the PCRPlength (264), and in still another embodiment the pillar lobe length(274) is no more than 50% of the PBP length (244), and no more than 40%,and 30% in further embodiments.

In one embodiment of the insert pillar (200), the pillar bore threads(232) extend at least 25 percent of the pillar bore length (236) fromthe pillar proximal end (210). In another embodiment, the pillar borethreads (232) extend at least 25 percent of the pillar bore length (236)from the pillar distal end (220). In still a further embodiment thepillar bore threads (232) extend 25-75 percent of the pillar bore length(236) from either the pillar proximal end (210) or the pillar distal end(220). In yet another embodiment, the pillar bore threads (232) extendthe full length of the pillar bore (230).

Additionally, in one embodiment of insert pillar (200), the pillar borewidth (234) is 15 to 85 percent of the PBP width (242), seen in FIGS. 3and 5 b. In another embodiment, the pillar bore width (234) is 30 to 50percent of the PBP width (242). In still yet another embodiment, thepillar bore width (234) is less than 60 percent of the PBP width (242).The pillar spacing portion (250), in one embodiment, has a PSP width(252) that is greater than the PBP width (242). While in anotherembodiment, the PSP width (252) is 101-150 percent of the PBP width(242). In yet another embodiment, the PSP width (252) is 105-125 percentof the PBP width (242). Furthermore, in one embodiment of the pluralitypillar lobes (270), the pillar lobe second width (273), seen in FIG. 4 ,is 50 to 95 percent of the pillar lobe first width (272). In anotherembodiment, the pillar lobe second width (273) is 60 to 90 percent ofthe pillar lobe first width (272). In still yet another embodiment, thepillar lobe second width (273) is less than 85 percent of the pillarlobe first width (272).

The previously mentioned clip (300), as seen in FIGS. 7-9 , engages theinsert pillar (200) at the pillar clip receiving portion (260) and keepsthe pillar (200) and the base plate (400) connected together, as seen inFIGS. 14 and 19-21 . As seen in FIGS. 7-9 , the clip (300) may furtherinclude a clip proximal end (310), a clip distal end (320), a clip width(330), a clip length (340), a clip height (350), a clip first radius(360), a clip second radius (370), and a clip retention protrusion (380)having a clip retention protrusion radius (382). The clip length (340)is the distance between the clip proximal end (310) and the clip distalend (320), as seen in FIG. 7 . When the clip (300) is installed on theinsert pillar (200), the clip width (330) is 115 to 200 percent largerthan the PBP width (242), seen in FIG. 5 b , in one embodiment. Inanother embodiment, the clip width (330) is 120 to 175 percent largerthan the PBP width (242). In yet another embodiment, the clip width(330) is less than 150 percent of the PBP width (242). Furthermore, inone embodiment of clip (300) installed on the insert pillar (200), theclip height (350) is 40 to 90 percent of the clip width (330). Yet inanother embodiment, the clip height (350) is 60 to 75 percent of theclip width (330). In still yet another embodiment, the clip height (350)is greater than 65 percent of the clip width (330). The clip firstradius (360) is located along the clip's (300) outside edge, and theclip second radius (370) is located along the clip's (300) internaledge, as seen in FIG. 8 . In one embodiment of clip (300) the clipsecond radius (370) is 55 to 90 percent of the clip first radius (360).In another embodiment, the clip second radius (370) is 65 to 85 percentof the clip first radius (360). In yet another embodiment, the clipsecond radius (370) is greater than 70 percent of the clip first radius(360). The earlier mentioned clip retention protrusions (380) engage theinsert pillar (200) in the pillar clip receiving portion (PCRP) (260),as seen in FIG. 9 . Furthermore, each clip retention protrusion (380)has a clip retention protrusion radius (382), as illustrated in FIG. 8 .In one embodiment of clip (300), the clip retention protrusion radius(382) is 12 to 30 percent of the clip first radius (360). In anotherembodiment, the clip retention protrusion radius (382) is 15 to 25percent of the clip first radius (360). In still another embodiment, theclip retention protrusion radius (382) is less than 27 percent of theclip first radius (360).

Now referring to FIGS. 10-14 , the base plate (400) may include a baseplate proximal end (410), a baseplate distal end (420), a base platewidth (430), a base plate length (440), defined as the distance betweenthe base plate proximal end (410) and the baseplate distal end (420), abase plate bore (450) having a base plate bore width (452), seen in FIG.12 , and a base plate bore length (454), seen in FIG. 10 . The baseplate bore (450) extends through the base plate (400), which is why thebase plate bore length (454) is the same as the base plate length (440)in FIG. 10 . The base plate bore (450) may be formed with a plurality ofbase plate pillar lobe engagement recesses (460), abbreviated BPPLER, orother complimentary geometry designed to engage the pillar lobes (270).Many of the disclosed embodiments offer the additional benefit ofimproved stress distribution, ease of manufacturing, and easy ofassembly. As seen in FIG. 12 , in various embodiments the plurality ofbase plate pillar lobe engagement recesses (460) may form an overallnon-circular recess having a BPPLER first width (462), a BPPLER secondwidth (464), a BPPLER first radius (466) located on each of theplurality of base plate pillar lobe engagement recesses (460), and aBPPLER second radius (468) is located on each of the plurality of baseplate pillar lobe engagement recesses (460). The plurality of base platepillar lobe engagement recesses (460) extend radially outward from thebase plate bore (450) and extend a BBPLER length into the base plate(400) from the baseplate distal end (420), and the BBPLER length is lessthan the base plate bore length (454) thereby creating a pocket withinthe base plate (400) to receive the plurality of pillar lobes (270), andin one embodiment the BBPLER length is at least 25% less than the baseplate bore length (454), and the BBPLER length is 30-70% of the baseplate bore length (454) in a further embodiment.

The base plate (400) receives the pillar (200) from the base platedistal side (420) through the base plate bore (450), as seen in FIG. 13. Additionally in one embodiment of base plate (400), the base platebore width (452), seen in FIG. 11 , is 20 to 70 percent of the baseplate width (430). While in another embodiment, the base plate borewidth (452) is 25 to 60 percent of the base plate width (430). In yetanother embodiment, the base plate bore width (452) is less than 55percent of the base plate width (430). The plurality of base platepillar lobe engagement recesses (460) are designed to receive andcooperate with the plurality of pillar lobes (270) to prevent the pillar(200) from rotating with respect to the base plate (400), as seen inFIGS. 12 and 13 . In one embodiment of pillar (200) and base plate(400), the pillar lobe first width (272) is 55 to 97.5 percent of theBPPLER first width (462). In another embodiment, the pillar lobe firstwidth (272) is 70 to 95 percent of the BPPLER first width (462). In yetanother embodiment, the pillar lobe first width (272) is greater than 85percent of the BPPLER first width (462). Similarly, one embodiment has apillar lobe second width (273) that is 55 to 97.5 percent of the BPPLERsecond width (464). In another embodiment, the pillar lobe second width(273) is 70 to 95 percent of the BPPLER second width (464). In yetanother embodiment, the pillar lobe second width (273) is greater than85 percent of the BPPLER second width (464). Additionally, in oneembodiment the pillar lobe first radius (276) is approximately equal tothe BPPLER first radius (466), while in a further embodiment the pillarlobe first radius (276) is less than the BPPLER first radius (466), andin another embodiment the pillar lobe first radius (276) is 65 to 97.5percent of the BPPLER first radius (466), as seen in FIG. 13 . Inanother embodiment, the pillar lobe first radius (276) is 80 to 95percent of the BPPLER first radius (466). While in yet anotherembodiment, the pillar lobe first radius (276) is greater than 85percent of the BPPLER first radius (466).

Furthermore, in one embodiment the pillar lobe second radius (278) isapproximately equal to the BPPLER second radius (468), while in afurther embodiment the pillar lobe second radius (278) is less than theBPPLER second radius (468), and in another embodiment the pillar lobesecond radius (278) is 65 to 97.5 percent of the BPPLER second radius(468). In another embodiment, the pillar lobe second radius (278) is 80to 95 percent of the BPPLER second radius (468). In yet anotherembodiment, the pillar lobe second radius (278) is greater than 85percent of the BPPLER second radius (468).

It should be noted that the illustrated embodiments show a pillar (200)having four pillar lobes (270) and a base plate (400) having four baseplate pillar lobe engagement recesses (460); however, that the pillarlobes (270) and base plate pillar lobe engagement recesses (BPPLER)(460) are not limited to four pillar lobes (270) and four base platepillar lobe engagement recesses (BPPLER) (460), in fact one embodimentonly has two lobes and recessed, while another embodiment has three totwelve. Further, one embodiment has just one pillar lobe (270) and onebase plate pillar lobe engagement recess (460). In still yet anotherembodiment, there may be a plurality of pillar lobes (270) resembling agear with up to 24 lobes and recesses. However, as previously mentioned,the disclosed relationships and geometries improve stress distributionthroughout this multi-component system.

FIGS. 15-18 show various views of the support ring (500). The supportring (500) sits on the base plate proximal end (410), as seen in FIGS.19-21 , and supports and aligns both the prong ring (700) and theretainer latch (800) and prevents them from rotating in respect to eachother, as seen in FIGS. 31-33 and 37-38 . As seen in FIGS. 15 and 16 ,the support ring (500) may include a support ring proximal end (510), asupport ring distal end (520), a support ring inner width (530), asupport ring outer width (540), a support ring length (550), as definedas the distance between the support ring proximal end (510) and thesupport ring distal end (520), and a plurality of support ring alignmentprotuberances (560), abbreviated SRAP. The plurality of support ringalignment protuberances (560) have a SRAP width (562), seen in FIG. 16 ,which is the distance that the support ring alignment protuberances(560) extends radially away from a support ring exterior surface (542)defining the support ring outer width (540), a SRAP length (564), seenin FIG. 18 , a SRAP sinistral edge (566), a SRAP dextral edge (568), anda SRAP sinistral to dextral edge angle (569), as seen in FIG. 17 . Thesupport ring (500) may include a support ring standoff (570),abbreviated SRS, having a SRS width (572), seen in FIG. 17 , a SRSlength (574), seen in FIG. 18 , a SRS sinistral edge (576), a SRSdextral edge (578), and a SRS sinistral to dextral edge angle (579). Inone embodiment of support ring (500), the support ring inner width (530)is 60 to 95 percent of the support ring outer width (540), seen in FIG.15 . In another embodiment, the support ring inner width (530) is 70 to90 percent of the support ring outer width (540). Additionally, thesupport ring length (550) is 25 to 85 percent of the base plate length(440), in one embodiment of support ring (500). In another embodiment,the support ring length (550) is 35 to 70 percent of the base platelength (440). In still yet another embodiment, the support ring length(550) is less than 60 percent of the base plate length (440).

Furthermore, in one embodiment of support ring alignment protuberances(560) and support ring standoff (570), the SRAP width (562) is 50 to 200percent of the SRS width (572), seen in FIG. 17 . In another embodiment,the SRAP width (562) is 75 to 150 percent of the SRS width (572). Instill another embodiment, the SRAP width (562) is less than 125 percentof the SRS width (572). Additionally, in another embodiment the SRAPlength (564), seen in FIG. 18 , is 20 to 80 percent of the support ringlength (550), seen in FIG. 15 , and 30 to 70 percent in anotherembodiment, and no more than 60 percent in still a further embodiment.

In the embodiment of FIG. 16 , each of the plurality of support ringalignment protuberances (560) have SRAP sidewalls (561) extending fromthe support ring exterior surface (542) to a SRAP exterior surface(563). A SRAP sidewall angle (565) exists between a SRAP sidewall (561)and a line tangent to the support ring exterior surface (542) at itsintersection with the SRAP sidewall (561), as shown in FIG. 16 . In oneembodiment the SRAP sidewall angle (565) is acute, while in a furtherembodiment it is no more than 85 degrees, and in still anotherembodiment it is at least 70 degrees, or at least 75 degrees. Theintersection of the SRAP sidewall with the support ring exterior surface(542) establishes the points for determining the SRAP sinistral todextral edge angle (569). Further, as seen in the embodiment of FIG. 17, a support ring inner surface (544) intersects with the SRS sinistraledge (576) and the SRS dextral edge (578). An imaginary line tangent tothe support ring inner surface (544) at the intersection defines a SRSedge angle (577) measured to the SRS sinistral edge (576) or the SRSdextral edge (578). In one embodiment the SRS edge angle (577) isobtuse. The intersection of the support ring inner surface (544) withthe SRS sinistral edge (576) and the SRS dextral edge (578) alsoestablishes the points used to define the SRS sinistral to dextral edgeangle (579).

In one embodiment the SRAP sinistral to dextral edge angle (569) isapproximately equal to the SRS sinistral to dextral edge angle (579),while in another embodiment the SRS sinistral to dextral edge angle(579) is greater than the SRAP sinistral to dextral edge angle (569),and in a further embodiment the SRS sinistral to dextral edge angle(579) is at least twice the SRAP sinistral to dextral edge angle (569).Further embodiments cap this relationship recognizing diminishingreturns and negative consequences such that the SRS sinistral to dextraledge angle (579) is no more than six times the SRAP sinistral to dextraledge angle (569), no more than five time in another embodiment, no morethan four times in a further embodiment, and no more than three times instill another embodiment. The SRS length (574), seen in FIG. 18 , is 40to 95 percent of the support ring length (550), seen in FIG. 15 , in oneembodiment. In another embodiment, the SRS length (574) is 50 to 85percent of the support ring length (550), while in an even furtherembodiment the SRS length (574) is at least 60 percent of the supportring length (550). As with all of the disclosed relationships, theserelationships are far more than mere optimization of a variable, andthey recognize trade-offs and negative consequences of merely optimizinga single component in a complex multi-component system to achieveimproved stress distribution, ease of manufacturing, and easy ofassembly.

In the embodiment of FIGS. 22-24 , the spring (600) encircles the pillar(200) and is used to bias the top insert (900) in a direction away fromthe base plate (400). The spring (600) may include a spring proximal end(610), a spring distal end (620), a spring outer width (630), a springinner width (640), a spring length (650), defined as the distancebetween the spring proximal end (610) and the spring distal end (620), aspring material width (660) defined as the spring outer width (630)minus the spring inner width (640) and afterwards dividing thedifference by two, and a coil space distance (670), defined as thedistance between adjacent turns of the wire forming the spring (600)when in an unloaded state. The term spring (600) is meant to encompassany biasing mechanism, unless specifically stated to incorporatefeatures and attributes such as those disclosed with respect to theillustrated embodiments.

The spring proximal end (610) abuts against the top insert (900), asseen in FIG. 2 . The spring distal end (620) abuts against the baseplate proximal end (410), with the pillar traversing the center of thespring (600), as seen in FIG. 24 . The spring outer width (630) is 100to 250 percent of the PBP width (242), in one embodiment. In anotherembodiment, the spring outer width (630) is 120 to 190 percent of thePBP width (242). In still another embodiment, the spring outer width(630) is greater than 140 percent of the PBP width (242). Similarly, inanother embodiment the spring inner width (640) is 100 to 240 percent ofthe PBP width (242). In another embodiment, the spring inner width (640)is 105 to 180 percent of the PBP width (242). In yet another embodiment,the spring inner width (640) is greater than 110 percent of the PBPwidth (242). Furthermore, one embodiment of spring (600) may have aspring length (650) that is 110 to 250 percent of the PBP length (244).In another embodiment, the spring length (650) is 125 to 200 percent ofthe PBP length (244). In yet another embodiment, the spring length (650)is greater than 150 percent of the PBP length (244). The spring coilspace distance (670) may be 50 to 300 percent larger than the springmaterial width (660) in one embodiment. While in another embodiment, thespring coil space distance (670) may be 755 to 200 percent larger thanthe spring material width (660). In yet another embodiment, the springcoil space distance (670) is at least 100 percent larger than the springmaterial width (660). It should be noted that the spring (600) does nothave to be a helical wound spring. For instance in one embodiment, notshown in the drawings, the spring (600) mechanism may be, but notlimited to a wave spring, a leaf spring, a tension spring, an airbladder biasing mechanism, and/or a viscoelastic biasing mechanism.Furthermore, it should be noted that some embodiments of fastener (100)may forgo a separate and distinct spring (600) mechanism. For example,an embodiment may have a biasing mechanism that is an un-separable andinnate part of the top insert (900), base plate (400), and/or supportring (500), not illustrated in the drawings. FIG. 25 is an isometricdrawing, and FIG. 26 is top plan view of an embodiment showing how thepillar (200), clip (300), base plate (400), support ring (500), and thespring (600) are positioned in respect to each other. It should be notedthat during the assembly of the fastener (100) other parts not discussedmay be installed, and the drawings should not be considered to be orderof assembly sequence.

The prong ring (700), as seen in FIGS. 27-33 , may include a prong ringproximal end (710), a prong ring distal end (720), a prong ring firstwidth (730), a prong ring second width (740), a prong ring first length(750), seen in FIG. 30 , a prong ring second length (752), a prong ringbore (760), having a prong ring bore width (762), and a plurality ofprongs (770), each having a prong width (772), a prong length (774), aprong first separation angle (776), a prong second separation angle(778), which in some embodiments defines the extend of an interlockingmechanism (790), and a prong latch (780). The prong latch (780) may havea prong latch width (782); a prong latch length (784), and a prong latchangle (785). In the illustrated embodiments the prong ring proximal end(710) is positioned towards the top insert (900), and the prong ringdistal end (720), and/or interlocking mechanisms (790), rests upon thebase plate (400), as seen in FIGS. 31 and 32 . The prong ring firstwidth (730) is substantially the same as the base plate width (430).Additionally in one embodiment of prong ring (700), the prong ringsecond width (740) is 70 to 97.5 percent of the prong ring first width(730). In another embodiment, the prong ring second width (740) is 75 to95 percent of the prong ring first width (730). While in anotherembodiment, the prong ring second width (740) is less than 85 percent ofthe prong ring first width (730). The prong ring first length (752) is100 to 150 percent of the PBP length (244) in one embodiment of prongring (700). In another embodiment, the prong ring first length (752) is120 to 140 percent of the PBP length (244). While in another embodiment,the prong ring first length (752) is greater than 125 percent of the PBPlength (244). Additionally, in one embodiment the prong ring secondlength (752) is 125 to 200 percent of the SRAP length (564). While inanother embodiment, the prong ring second length (752) is 140 to 180percent of the SRAP length (564). In yet another embodiment, the prongring second length (752) is greater than 150 percent of the SRAP length(564).

In the illustrated embodiment the prong ring bore (760) at leastpartially encircles both the pillar body portion (PBP) (240) and thespring (600), as seen in FIGS. 32 and 33 . Furthermore, the prong ringbore width (762) is sufficiently large enough to allow passage of thespring (600). In one embodiment the prong ring bore width (762) is suchthat the spring (600) must be radially deformed to fit within the prongring bore (760).

Now directing our attention to the plurality of prongs (770), as seen inFIG. 30 . In one embodiment, each prong (770) has a prong width (772)that is 10 to 70 percent of the prong length (774). In anotherembodiment, the prong width (772) is 20 to 60 percent of the pronglength (774). In yet another embodiment, the prong width (772) is atleast 25 percent of the prong length (774), and no more than 50 percentof the prong length (774) in still a further embodiment. The prong firstseparation angle (776) and prong second separation angle (778), as seenin FIG. 28 , are configured to be geographically coordinated so theprong ring (700) may engage the top insert (900), the base plate (400),and/or the support ring (500). In one embodiment, the plurality ofprongs (770) are arraigned in several dyads. The angle formed by thedyad prongs (770) closest to each other form the prong first separationangle (776) seen in FIG. 28 . Similarly, the angle formed between theprong dyads, and/or the boundary of the interlocking mechanism (790),form the second separation angle (778). FIG. 28 shows an embodiment thathas a total of twelve prongs (770) forming six prong (770) dyads. Theinvention is not limited by the number of prongs (770), prong (770)grouping, or number of interlocking mechanisms (790). For example, oneembodiment may have only ten prongs (770) forming five prong (770)dyads. While another embodiment may have eight prongs (770) forming fourprong (770) dyads. In still yet another embodiment may have a total oftwelve prongs (770) forming 4 prong (770) triads.

In the illustrated embodiments a prong latch (780) is located on eachprong (770). The prong latch (780) engages and latches the top insert(900) into place when the fastener (100) is pressed into the panelaperture (PA). The prong width (782) is a function of the prong latchlength (784) and the prong latch angle (785). In one embodiment theprong first separation angle (776) is no more than the prong secondseparation angle (778), while in a further embodiment the prong firstseparation angle (776) is at least 10% less than the prong secondseparation angle (778), and at least 20% less, and 30% less in furtherembodiments. However, another series of embodiments sets a floor on thisrelationship such that the prong first separation angle (776) is atleast 15% of the prong second separation angle (778), and at least 25%,35%, and 45% in further embodiments.

Now addressing the retainer latch (800) as seen in FIGS. 33-38 . Theretainer latch (800) rest upon the base plate (400), and may at leastpartially encircle the support ring (500) and/or the prong ring (700),as seen in FIG. 37 . The retainer latch (800) engages and locks with aportion of the support ring (500), namely, in the illustratedembodiments, the support ring alignment protuberances (560), whichprevents both rotational and linear movement of the retainer latch (800)in relation to the support ring (500). As seen in FIG. 36 , the retainerlatch (800) may include a retainer latch proximal end (810), a retainerlatch distal end (820), a retainer latch length (822) defined as thedistance between the retainer latch proximal end (810) and the retainerlatch distal end (820), and a retainer latch ring (830), which mayinclude a retainer latch ring proximal end (832), a retainer latch ringdistal end (834), a retainer latch ring width (836), a retainer latchring length (837) defined as the distance between the retainer latchring proximal end (832) and the retainer latch ring distal end (834), aretainer latch ring thickness (838), and a retainer latch ring expansionslot (839), seen in FIG. 35 , and a plurality of retainer latchprojections (840), abbreviated RLP, each having: a RLP proximal end(842), a RLP distal end (844), a RLP width (845), a RLP length (846)defined as the distance between the RLP proximal end (842) and the RLPdistal end (844), a RLP tilt angle (848), and a RLP separation angle(849).

The retainer latch ring (830) provides the framework of which theplurality retainer latch projections (840) are attached, integrally orotherwise, and also encircles at least a portion of the support ring(500) and/or the prong ring (700). In one embodiment, the retainer latchring (830) has a plurality of recesses in the inner surface of theretainer latch ring (830) to accept and cooperate with the plurality ofsupport ring alignment protuberances (560) thereby preventing rotationaland/or linear movement of the retainer latch (800) in relation to thesupport ring (500). In another embodiment, the retainer latch ring (830)has a plurality of apertures in the retainer latch ring (830) to acceptand cooperate with the plurality of support ring alignment protuberances(560), thereby preventing both rotational and linear movement of theretainer latch (800) in relation to the support ring (500), as seen inFIG. 37 .

As seen in FIG. 36 , in one embodiment of an uninstalled state retainerlatch (800), the retainer latch ring length (837) is 15 to 65 percent ofthe retainer latch length (822). In another uninstalled stateembodiment, the retainer latch ring length (837) is 25 to 50 percent ofthe retainer latch length (822). In yet another uninstalled stateembodiment, the retainer latch ring length (837) is less than 50 percentof the retainer latch length (822). The retainer latch ring width (836)is 75 to 125 percent of the prong ring first width (730), in oneembodiment of fastener (100). In another embodiment, the retainer latchring width (836) is 85 to 115 percent of the prong ring first width(730). In yet another embodiment, the retainer latch ring width (836) isless than 105 percent of the prong ring first width (730). FIG. 35 showsan embodiment of retainer latch (800) having a retainer latch ringthickness (838). In one embodiment, the retainer latch ring thickness(838) is 5 to 65 percent of the prong width (772), seen in FIG. 30 . Inanother embodiment, the retainer latch ring thickness (838) is 10 to 50percent of the prong width (772). In yet another embodiment, theretainer latch ring thickness (838) is less than 25 percent of the prongwidth (772). FIG. 35 also shows an embodiment of retainer latch (800)having a retainer latch ring expansion slot (839). The retainer latchring expansion slot (839) allows the retainer latch ring width (836) tobe temporarily enlarged in order to install the retainer latch (800) onthe support ring (500). In one embodiment the retainer latch ringexpansion slot (839) has a width that is at least 2.5% of the retainerlatch ring width (836), and at least 5%, and at least 7.5% in furtherembodiments. Another series of embodiments caps this relationship sothat the width of the retainer latch ring expansion slot (839) is nomore than 35% of the retainer latch ring width (836), and no more than25%, and 15% in further embodiments.

The retainer latch (800) has a plurality of retainer latch projections(840), as the embodiment in FIG. 34 illustrates. When the fastener (100)is pressed into a panel aperture (PA), the RLP proximal end (842)deflect during insertion and then rebound after passing below the outerskin, thereby engaging the top inside surface of the panel (P) andlocking the fastener (100) into place. The RLP distal end (844) ispermanently attached to the retainer latch ring (830), as seen in FIG.34 . Additionally, in one embodiment the RLP width (845) is 30 to 80percent of the RLP length (846). In another embodiment, the RLP width(845) is 40 to 70 percent of the RLP length (846). In anotherembodiment, the RLP width (845) is less than or equal to 60 percent ofthe RLP length (846). The plurality of retainer latch projections (840)have a RLP tilt angle (848) with respect to the retainer latch ring(830), as seen in FIG. 34 . The RLP tilt angle (848) cause the pluralityof retainer latch projections (RLP) (840) to spread out in respect tothe longitudinal axis of the fastener (100). When the fastener (100) isbeing pressed in the panel aperture (PA), the plurality of retainerlatch projections (840) deflect toward the longitudinal axis as theypass through the panel (P) skin. Once the plurality of retainer latchprojections (840) clear the panel (P) skin they spring back to theirinitial state with the RLP proximal ends (842) located beneath the panel(P) skin, thereby locking the fastener within the panel aperture (PA).In one embodiment the prong separation angle (778), seen in FIG. 28 , isless than the RLP separation angle (849). The embodiment shown in FIG.35 shows a total of six retainer latch projections (840), but theinvention is not limited to having six retainer latch projections (840).For example, one embodiment of retainer latch (800) may have threeretainer latch projections (840); another embodiment may have fourretainer latch projections (840); while another embodiment may haveeight, or more, retainer latch projections (840). The number of retainerlatch projections (RLP) (840) is not limited to those listed in theprevious examples and can have multiple configurations.

Now addressing the top insert (900) seen in FIG. 39 . The top insert(900) may include a top insert proximal end (910), abbreviated TIPE,having a TIPE plate (912), a TIPE plate width (913), a TIPE bore (914),a TIPE plate bore width (916), a TIPE plate bore length (918), and a topinsert distal end (920), a top insert width (930), a top insert length(940), defined as the distance between the top insert proximal end (910)and the top insert distal end (920), a plurality of top insert supportcolumns (950), abbreviated TISC, each having a TISC width (952), a TISClength (954), a TISC height (955), and a TISC separation angle (956), aswell as a plurality of top insert latching projections (960),abbreviated TILP, each having a TILP width (962), a TILP length (964), aTILP separation angle (966), and a TILP latch (968), as well as a topinsert connection ring (970), abbreviated TICR, having a TICR proximalend (972), a TICR distal end (974), a TICR width (976), a TICR length(977), and a TICR thickness (978).

During the installation of the fastener (100) into the panel aperture(PA), pressure is applied to the top insert proximal end (910),abbreviated TIPE, thereby pressing and locking the fastener (100) intoplace. Each of the plurality of top insert support columns (950),abbreviated TISC, are attached to the TIPE plate (912) located at thetop insert proximal end (910).

Additionally, the spring proximal end (610) biases against the TIPEplate (912), as seen in FIGS. 2, 37 and 43 . Furthermore, each of theplurality of the top insert support columns (950) are connected to theTICR proximal end (972) of the top insert connection ring (970), as seenin FIGS. 39, 40 and 42 . Additionally in one embodiment of top insert(900), the TISC width (952), seen in FIG. 39 , is 10 to 60 percent ofthe TISC length (954), seen in FIG. 42 . In another embodiment the TISCwidth (952) is less than or equal to 50 percent of the TISC length(954). In one embodiment of top insert (900), the TISC separation angle(956), seen in FIG. 40 , is 30 to 200 percent of the TIMP separationangle (966). In another embodiment, the TISC separation angle (956) is50 to 125 percent of the TIMP separation angle (966). In yet anotherembodiment, the TISC separation angle (956) is less than or equal to 90percent of the TIMP separation angle (966).

In similar fashion to the top insert support columns (950) beingconnected to the TICR proximal end (972) of the top insert connectionring (970), the plurality of top insert latching projections (960) areattached to the TICR proximal end (972) of the top insert connectionring (970). In one embodiment of top insert (900), the TILP width (962),seen in FIG. 42 , is 30 to 90 percent of the TILP length (964). While inanother embodiment the TILP width (962) is 45 to 80 percent of the TILPlength (964). In yet another embodiment, the TILP width (962) is greateror equal to 50 percent of the TILP length (964). The TILP separationangle (966) is large enough to accommodate at least one prong (770) anda top insert column (950), while maintaining alignment of the prong(770) and the top insert (900), as seen in FIGS. 41 and 44 .Furthermore, in an embodiment each of the plurality of top insertprojections (960) has at least one TILP latch (968) which engages theinner surface of a panel (P) skin once the fastener (100) is installed.The top insert width (930), seen in FIG. 40 , is defined as the distancebetween a TILP latch (968) and a TILP latch (968) on the opposite sideof the top insert (900). Additionally, the top insert width (930) in theuninstalled state is larger than the panel aperture (PA). Like theplurality of retainer latch projections (840), the plurality of topinsert latching projections (960) flex towards the center of thefastener (100) during installation in the panel aperture (PA), causingthe top insert width (930) to decrease. Once the fastener (100) has beenpressed into its final position the plurality of top insert latchingprojections (960) spring outwards once they clear the panel (P) skinsurrounding the panel aperture (PA); thereby locking the fastener (100)in place. Having multiple components incorporating this characteristicincreases the reliability and safety of the fastener (100), but also thecomplexity.

In order to allow for clearance of the plurality of top insert latchingprojections (TILP) (960) while they are flexing towards the center ofthe fastener (100), the TIPE plate width (913), seen in FIG. 40 , isless than the TICR width (976), seen in FIG. 41 . In one embodiment oftop insert (900), the TIPE width (913) is 60 to 95 percent of the TICRwidth (976). In another embodiment the TIPE width (913) is 65 to 90percent of the TICR width (976). In still another embodiment the TIPEwidth (913) is less than or equal to 85 percent of the TICR width (976).Additionally, in one embodiment the TICR thickness (978), seen in FIG.41 , is 30 to 90 percent of the TISC height (955), seen in FIG. 40 . Inanother embodiment the TICR thickness (978) is 40 to 80 percent of theTISC height (955). In yet another embodiment the TICR thickness (978) isat least 50 percent of the TISC height (955), as seen in FIG. 40 . TheTIPE bore (914) is located in the center of the TIPE plate (912) andsubstantially aligns with the pillar proximal end (210) when thefastener (100) is in a fully assembled state, as seen in FIGS. 1 and 44. Consequently, in one embodiment the TIPE bore width (916), seen inFIG. 40 , is larger than the pillar bore width (234), seen in FIG. 5 a ,while in another embodiment the TIPE bore width (916) is larger than thePBP width (242). In one embodiment of top insert (900), the TIPE borewidth (916) at least 10% greater than the pillar bore width (234), andat least 20%, 30%, and 40% greater in additional embodiments. Whileanother series of embodiments caps this relations and has the TIPE borewidth (916) no more than 200% greater than the pillar bore width (234),an no more than 175%, 150%, and 125% greater in additional embodiments.Additionally in one embodiment the TIPE plate bore length (918), seen inFIG. 39 , is 50 to 200 percent of the TICR length (977), seen in FIG. 42. While in another embodiment, the TIPE plate bore length (918) is 75 to175 percent of the TICR length (977). In yet another embodiment, theTIPE plate bore length (918) is 90 to 125% of the TICR length (977).

FIGS. 45-101 illustrate additional embodiments of the fastener (100). Asseen in FIGS. 47 and 74 , these embodiments may incorporate a similarinsert pillar (200), which is received in a base plate (400), bothcontaining similar cooperating structures and attributes as previouslydisclosed. The spring (600) of this embodiment cooperates with the baseplate (400) and is entrapped by the top insert (900). These embodimentsmay also include a base plate foundation (480) entrapping the insertpillar (200) at least partially within the base plate (400).

With respect to the insert pillar (200) of FIG. 45 and later, all of thedisclosure relating to FIGS. 1-44 applies and will not be repeated forthe sake of brevity. With respect to the base plate (400) of FIG. 45 andlater, all of the disclosure relating to FIGS. 1-44 applies and will notbe repeated for the sake of brevity. Notable differences in the insertpillar (200) of FIG. 45 and later include the lack of a pillar spacingportion (250) and pillar clip receiving portion (260), seen in FIG. 3 ,as they are not needed in these later embodiments. Further, notabledifferent in the base plate (400) of FIG. 45 and later include theaddition of a base plate pillar shroud (470) extending from the baseplate (400), as seen in FIG. 52 . As illustrated, the base plate length(440) in this embodiment extends from the base plate distal end (420) tothe transition in diameter, or shelf, created by the base plate pillarshroud (470), therefore all the relationships discussed with respect toFIGS. 1-44 and the base plate length (440) are applicable to the laterembodiments.

The base plate pillar shroud (470), abbreviated BPPS, may be integralwith the base plate (400) or permanently attached to it. The base platepillar shroud (470) has a BPPS proximal end (472), a BBPS distal end(474), a BBPS width (476), and a BBPS length (478), as seen in FIG. 53 .The BBPS width (476) is at least 5% less than the base plate width(430), shown in FIG. 11 and applicable to the base plate distal end(420) of FIG. 53 , and in a further embodiment it is at least 10% less,and at least 15% less in still another embodiment. However, in anotherseries of embodiments ensuring adequate wall thickness of the base platepillar shroud (470), the BBPS width (476) is at least 40% of the baseplate width (430), and at least 50%, and 60% in further embodiments.Additionally, the BBPS length (478) is at least 50% greater than thebase plate length (440), and at least 75% greater, 100% greater, and125% greater in further embodiments. However, another series ofembodiments caps this relationship so that the BBPS length (478) is nomore than 300% greater than the base plate length (440), and no morethan 250% greater, and 200% greater in additional embodiments.

The base plate (400) may further include one or more bonding recesses(490), as seen in FIGS. 52-53 , and equally as applicable to allembodiments, which help with the torsional strength of the fastener(100) if it is bonded, via epoxy or other potting agent, in the panel(P). In one embodiment the volume of the one or more bonding recesses(490) is at least 2.5% of the volume of the base plate (400). The volumeof the bonding recess (490) is determined by filling the recesses withclay until it is indistinguishable from the contour of the adjacentportions of the base plate (400), then removing the clay and measuringthe volume via a water displacement method, and comparing it to thevolume of the base plate (400), also determined using a waterdisplacement method. In an additional embodiment the volume of the oneor more bonding recesses (490) is at least 5% of the volume of the baseplate (400), and at least 7.5% and 10% in further embodiments. In oneembodiment the bonding recesses (490) align with aspects of the spring(600) and/or top insert (900) to ensure bonding material may flow froman insertion point at the fastener proximal end (110) to the fastenerdistal end (120). For example in FIG. 66 the bonding recess (490) alignswith a spring slot (680), formed in the spring (600) so that bondingmaterial may easily move from the spring slot (680) to the bondingrecess (490). While the radial depth of the bonding recess (490) shownin FIG. 66 is not illustrated as being such that a portion of thebonding recess (490) is located a recess proximity distance from thelongitudinal axis of the fastener (100) that is less than an adjacentdistance from the exterior surface of the spring (600) to thelongitudinal axis, in one embodiment, not illustrated but easilyunderstood, the recess proximity distance is such that a portion of thebonding recess (490) is within the boundary of the spring slot (680) atthe spring distal end (620) to further promote the flow of bondingagent.

Sticking with the current subject of insertion of bonding agent, as seenin FIGS. 67-69 , the top insert (900) may include openings at the topinsert proximal end (910), adjacent to and/or behind the top insertlatching projections (960), to easily insert bonding agent permittingflow into the panel aperture as well as between the top insert (900) andthe spring (600), and out the spring distal end (620) to the bondingrecesses (490). The opening created alongside the edges of the topinsert latching projection (960), seen in FIG. 68 , and the associatedTILP length (964) ensure that the bonding agent may enter the panelwithin the confines of the panel aperture, but then flow out of thefastener (100) through these voids, as well as the voids associated withthe remotely located top insert latching projections (960), and alsofill the adjacent voids in the cellular core structure of the panel (P).Locating the openings at the top insert proximal end (910), adjacent toand/or behind the top insert latching projections (960), ensures bondingagent solidifies behind the top insert latching projections (960) sothey cannot later deflect inward due to vibration and compromise theintegrity of the fastener.

While the illustrated embodiments, such as seen in FIG. 66 , show thebonding recesses (490) as a pocket that does not extend all the way tothe base plate distal end (420), in a further embodiment the bondingrecess (490) does extend all the way to the base plate distal end (420).In fact, in another embodiment, not illustrated but easily understood,the bonding recess (490) extends along the external surface of the baseplate pillar shroud (470), and may extend all the way to the base plateproximal end (410), in other words, the full length of the base platefoundation length (478), while in one embodiment it extends throughoutat least 50% of base plate foundation length (478), and in still anotherembodiment throughout at least 75% of the base plate foundation length(478). Thus, these embodiments with bonding recesses (490) extendingalong the external surface of the base plate pillar shroud (470) areanalogous to the spring slots (680) seen in FIG. 62 , and thus all thedisclosure related to the size and location of the spring slots (680)applies equally to bonding recesses (490) extending along the externalsurface of the base plate pillar shroud (470).

Now sticking with the current subject of insertion of bonding agent, asseen in FIGS. 62-66 and 89-93 , the spring (600) may further include atleast one spring slot (680). The spring slot (680) has a spring slotwidth (682), a spring slot length (684), and a spring slot depth (686).The spring slot depth (686) is at least 0.25 mm in one embodiment, andat least 0.50 mm, and at least 0.75 mm in further embodiments, therebyensuring flow of the bonding agent. However, a further series ofembodiments caps the range so as to not negatively impacting theperformance of the spring (600), and in one such embodiment the springslot depth (686) is no greater than 5.0 mm, and no greater than 4.0 mm,3.0 mm, 2.0 mm, and 1.0 mm in still further embodiments. Further, thespring slot width (682) is at least 75% of the spring slot depth (686)in one embodiment, and at least 100% in another embodiment, and at least125% in still a further embodiment. However, a further series ofembodiments caps the range so as to not negatively impacting theperformance of the spring (600), and in one such embodiment the springslot width (682) no more than 300% of the spring slot depth (686), andno more than 250%, 225%, and 200% in further embodiments. Still further,the spring slot length (684) is greater than the spring slot width (682)and/or the spring slot depth (686) in one embodiment, and at least 50%greater than the spring slot width (682) and/or the spring slot depth(686) in another embodiment, and at least 75%, 100%, and 125% greater infurther embodiments. However, a further series of embodiments caps therange so as to not negatively impacting the performance of the spring(600), and in one such embodiment the spring slot length (684) is nomore than 12 times greater than the spring slot width (682) and/or thespring slot depth (686) in one embodiment, and no more than 10 times, 8times, and 6 times in further embodiments.

It is worth noting that the pillar bore (230) need not extend entirelythrough the insert pillar (200) in any of the embodiment, thus it mayreceive an external fastener from one side or both sides. For instancethe base plate foundation (480) illustrated in FIG. 47 does not have anaperture, although in additional embodiments, not shown but easilyunderstood, the base plate foundation (480) has an aperture permittingaccess to the pillar bore (230). The base plate foundation (480) entrapsthe pillar (200) within the base plate (400), and it may be attached tothe base plate (400) via welding, including, but not limited to,resistance welding, spin welding, friction welding, and solvent welding,or brazing, soldering, and any adhesive technology. The base platefoundation (480) may include an external adhesive layer that isactivated, or exposed, prior to the fastener (100) being inserted intothe panel (P) so that it bonds against the internal skin of the panel(P) with the other end of the fastener (100) engaging the inside of theother panel skin, and the spring (600) biases the assembly to ensureadequate contact pressure as the adhesive layer cures. The presentdisclosure includes a method of installing the fastener (100) asdescribed throughout, and one step may be applying an adhesive to thebase plate foundation (480) and/or exposing an adhesive that resides onthe base plate foundation. Thus, in one embodiment the spring (600)provides a biasing pressure of at least 5 psi, and at least 10 psi, 15psi, and 20 psi in additional embodiments. Another series of embodimentscaps the biasing pressure so it is no greater than 150 psi in oneembodiment, and no greater than 130 psi in another embodiment, and nogreater than 110 psi in still a further embodiment. This externaladhesive layer may also be incorporated on the base plate distal end(420) and/or pillar distal end (220) of the embodiments of FIGS. 1-44 .Further, the embodiments of FIG. 45 and later may incorporate a insertpillar (200) that is permanently attached to the base plate (400), withor without the addition of the base plate foundation (480).

The base plate foundation (480), abbreviated BPF, has a BPF proximal end(482), a BPF distal end (484), a BPF width (486), and a BPF length(488), as seen in FIGS. 59-61 . In one embodiment the BPF width (486) isapproximately equal to the base plate width (430), and in a furtherembodiment is at least 2.5% less than the base plate width (430). Inanother embodiment the BPF length (488) is less than 60% of the baseplate length (440) and/or the pillar lobe length (274), and less than50%, and 40% in further embodiments.

A major difference in the illustrated embodiments of FIGS. 1-44 versusthe embodiments beginning with FIG. 45 has to do with the spring (600),seen best in FIGS. 62-66 and FIGS. 89-93 . Another major difference inthe illustrated embodiments of FIGS. 1-44 versus the embodimentsbeginning with FIG. 45 has to do with the top insert (900), seen best inFIGS. 67-71 and FIGS. 94-98 . While all of the disclosure relating tothe embodiments illustrated in FIGS. 39-43 apply to the laterembodiments of FIGS. 67-71 and FIGS. 94-98 , some additional features inthe later embodiments are worth noting, and may also be incorporated inthe embodiments of FIGS. 39-43 .

It is helpful to first address the top insert (900), and specificallythe fact that the embodiments of FIGS. 67-71 and FIGS. 94-98 incorporatetop insert latching projections (960) at locations other than at the topinsert proximal end (910), as in the illustrated embodiments of FIGS.39-43 . Specifically, the embodiments of FIGS. 67-71 and FIGS. 94-98also incorporate top insert latching projections (960) at the top insertdistal end (920), although they are not limited to the top insert distalend (920) and may be located between the top insert distal end (920) andthe top insert proximal end (910). While the top insert latchingprojections (960) at the top insert proximal end (910) are specificallyconfigured to engage an inner surface of the panel skin upon insertion,the top insert latching projections (960) at the top insert distal end(920), or in between the ends, are configured to engage the cellularcore structure of a panel (P) and increase the resistance to turningwithin the panel (P). Obviously, these top insert latching projections(960) must also be configured to pass through a panel aperture (PA) uponinsertion and then must deflect to engage the cellular core structure ofthe panel (P). As noted later in the disclosure, the disclosedpredetermined TILP displacement applies regardless of if the top insertlatching projection (960) is located at the top insert proximal end(910), the top insert distal end (920), or somewhere in between.Further, all the disclosed length, width, and relationships associatedwith the top insert latching projections (960) apply regardless of thelocation. For convenience any top insert latching projections (960) thatare not located adjacent the top insert proximal (910) will be referredto as offset latching projections. In one embodiment the offset latchingprojections are not inline with the top insert latching projections(960) located adjacent the top insert proximal (910), in other words, asseen in FIG. 69 the offset latching projections are angularly offsetfrom the top insert latching projections (960) located adjacent the topinsert proximal (910). In one embodiment the offset latching projectionsare angularly offset from the top insert latching projections (960)located adjacent the top insert proximal (910) such that they are midwaybetween adjacent top insert latching projections (960) located adjacentthe top insert proximal (910); while in a further embodiment they arenot necessarily midway but are angularly offset at least 10 degrees, andoffset at least 15 degrees in another embodiment, and at least 20degrees in still a further embodiment. The offset latching projectionsare deflected outward as the top insert (900) is forced into aninstalled position, thereby compressing the spring (600) in thedirection of the longitudinal axis of the fastener (100), which causesradial expansion of the spring (600) behind the offset latchingprojections and causing them to deflect outward, as illustrated best inFIGS. 100 and 101 . Thus, the spring (600) may be configured to create afriction fit so that the base plate (400), the spring (600), and the topinsert (900) remain together during handling prior to installation, orthere may be selective attachment with adhesive provided the disclosedmovement is achieved.

In the embodiments beginning with FIG. 45 , at least a portion of thespring (600) is compressed in the direction of the longitudinal axis ofthe fastener (100) thereby causing radial expansion of the top insertlatching projections (960) located near the top insert distal end (920),best seen in FIGS. 99-101 . The spring (600) may further include a TILPactivation feature (690), as seen in FIGS. 62 and 89 . In one embodimentthere is a TILP activation feature (690) for each offset latchingprojection and is located behind the associated offset latchingprojection. In the illustrated embodiments the TILP activation feature(690) is configured as a ramp that cooperates with the associated offsetlatching projection to enhance the radial displacement of the offsetlatching projection relative to the longitudinal compression of thespring (600). The TILP activation feature (690) has a TILP activationfeature width (692), a TILP activation feature length (694), and in someembodiments a TILP activation feature angle (696). The TILP activationfeature length (694) is greater than the TILP activation feature width(692) in an embodiment, and the TILP activation feature length (694) is25%, 50%, 75%, and 100% greater than the TILP activation feature width(692) in further embodiments. However, a further series of embodimentscaps the range so as to not negatively impacting the performance of thespring (600), and in one such embodiment the TILP activation featurelength (694) is no more than 5 times greater than the TILP activationfeature width (692) in an embodiment, and the no more than 4 times more,and 3 times more in further embodiments. In another embodiment the TILPactivation feature angle (696) is at least 3 degrees, and at least 6degrees and 9 degrees in further embodiments. However, a further seriesof embodiments caps the range so as to not negatively impacting theperformance of the spring (600), and in one such embodiment the TILPactivation feature angle (696) is no more than 30 degrees, and no morethan 25 degrees and 20 degrees in further embodiments. While the springslots (680) are illustrated on the external surface of the spring (600),they may likewise be formed on the internal surface of the spring (600).In one embodiment the fastener (100) has at least one spring slot (680)for every top insert latching projection (960), in another embodimentthere are two spring slots (680) for every top insert latchingprojection (960), as seen in comparing FIGS. 66 and 67 . Even further,at least one spring slot (680) aligns with the void created beside a topinsert latching projection (960) and the spring slot length (684) isequal to, or greater than, the TISC length (954), seen in FIG. 69 ,and/or equal to, or greater than, the TILP length (964). One embodimentincludes at least 4 spring slots (680), while further embodimentsinclude at least 6, 8, and 10. Another series of embodiments caps thenumber of spring slots (680) to ensure functionality while notnegatively influencing the performance of the spring (600), therefore inone such embodiment there are no more than 36 spring slots (680), and nomore than 28, 20, and 12 in further embodiments. In the embodimentsillustrated in FIG. 45 and later, the spring (600) is adjacent the baseplate pillar shroud (470), and in the illustrated embodiments encirclesthe base plate pillar shroud (470) a full 360 degrees, although this isnot required and the spring (600) may consists of multiple individualsections arranged around the base plate pillar shroud (470) to achievethe disclosed goals. In these embodiments the spring material width(660), like in FIGS. 1-44 , is defined as the spring outer width (630)minus the spring inner width (640) and afterwards dividing thedifference by two, but may also be thought of as a maximum springsidewall thickness, as illustrated in FIGS. 64 and 91 . In suchembodiments the spring (600) also has a minimum spring sidewallthickness, for instance within the spring slots (680), which in someembodiments is no more than 70% of the maximum spring sidewallthickness, and no more than 60% and 50% in further embodiments. However,another series of embodiments establishes a floor on the range with theminimum spring sidewall thickness being at least 15% of the maximumspring sidewall thickness, and at least 20% and 25% in furtherembodiments. In some embodiments any of these disclosed sidewallthickness relationships are true for at least 30% of the spring internalsurface area, and at least 40% and 50% in further embodiments.Additionally, the spring (600) may include a chamfered surface at thespring proximal end (610), forming a transition to the spring innerbore, but it may also include a curved surface, and in one embodiment aconcave surface toward the spring distal end (620). Further, the springlength (650), namely the shortest distance between the spring proximalend (610) and the spring distal end (620), is within 40% of the baseplate pillar shroud length (478), and within 30%, 20%, 10%, and 5% infurther embodiments. The geometry and relationships disclosed play a keyrole in achieving the goals disclosed throughout including thedeformation of the spring (600), the associated deflection of the topinsert latching projections (960), and the movement and forcerelationships.

As seen best in the sequence of FIGS. 99-101 , the fastener (100) isinserted in the panel (P) and the base plate foundation (480) engagesthe inner skin of the panel (P), often with a layer of adhesivetherebetween. At this point in FIG. 99 the spring (600) is largelyundeformed in the direction of the longitudinal axis of the fastener(100). Then, as shown in FIG. 100 , the top insert (900) is forcedtoward the fastener distal end (120), thereby compressing the spring(600) in the direction of the longitudinal axis of the fastener (100),and the top insert latching projections (960) located at, or adjacent,the top insert proximal end (910), deflect inwardly to pass through thepanel aperture. In the process the spring proximal end (610) deformsinwardly and over a portion of the base plate proximal end (410), and aportion of the spring (600) deforms outwardly thereby radially extendingthe offset latching projections, namely the top insert latchingprojections (960) that are not located at, or adjacent, the top insertproximal end (910). Eventually, as seen in FIG. 101 , the top insertlatching projections (960) located at, or adjacent, the top insertproximal end (910), pass the panel skin and deflect outwardly and engagean inner surface of the panel skin thereby securing the fastener (100)within the panel (P). At this point even more of the spring (600) hasbeen deformed inwardly and over a portion of the base plate proximal end(410) and thereby loading the fastener (100) and ensuring pressure atthe interface between the base plate foundation (480) and the panelskin, which ensures any adhesive in the interface cures while underpressure. At this point the offset latching projections have fullydeflected outward thereby reducing the risk of rotation of the fastener(100) via engagement with the panel's internal cellular structure. Thus,the longitudinal movement of the top insert (900) has resulted inselective deformation toward the center of the fastener (100) at thespring proximal end (610), as well as deformation away from the centerof the fastener (100) at locations near the offset latching projections,generally at or near the spring distal end (620). The internal surfaceof the top insert (900) may include at least one inward deformationpromotion feature to further assist with the inward deformation of thespring proximal end (610) to create the disclosed biasing. Such inwarddeformation promotion features may be similar to the spring TILPactivation feature (690), and may be a wedge, ramp, or protrusion.

In one embodiment the components are configured so that the longitudinalmovement of the top insert (900) is no more than 5 mm, and no more than4 mm, 3 mm, and 2 mm in further embodiments. Another series ofembodiments place a floor on the longitudinal movement range such thatin one embodiment it is at least 0.5 mm, and at least 1.0 mm, 1.25 mm,1.5 mm, and 1.75 mm in further embodiments. Further, in one embodimentassociated inward deformation of the spring proximal end (610) is atleast 0.30 mm, and at least 0.50 mm, 0.70 mm, and 0.90 mm in furtherembodiments. Additionally, in one embodiment the longitudinal movementof the top insert (900) and disclosed deformation of the spring (600)occurs when subjected to a longitudinal force of no more than 50 lbf,and no more than 40 lbf in another embodiment, and no more than 30 lbfin an even further embodiment. However, another series of embodimentsplaces a floor on the range recognizing the relationship between thelongitudinal force and the resulting biasing pressure once installed,thus in one embodiment the longitudinal force required to achieve thedisclosed longitudinal movement of the top insert (900) to install thefastener (100) is at least 5 lbf, and at least 10 lbf in anotherembodiment, and at least 15 lbf in still a further embodiment.

The material properties of the various components of the fastener areessential to the goals. In one embodiment the top insert (900) is formedof a material different than at least one of the other components; whilein a further embodiment the top insert (900) is formed of a materialdifferent than at least two of the other components, and at least 3 inan even further embodiment. In a further embodiment at least two of thefollowing components are formed of the same material: the insert pillar(200), the base plate (400), and the base plate foundation (470); and inanother embodiment at least three of the listed components are formed ofthe same material, and in another embodiment all three are formed of7075 aluminum alloy or an iron based superalloy, which in one embodimentis A286 stainless steel alloy. In another embodiment the top insert(900) is formed of a thermoplastic, and in a further embodiment has adensity of less than 1.5 g/cc, and in a further embodiment is formed ofa thermoplastic polyetherimide (PEI) resin. In a further embodiment thethermoplastic top insert (900) has a hardness of 100-150 on a Rockwell Rscale.

In still a further embodiment the spring (600) is formed of anelastomeric material, which in a further embodiment is an elastomericpolymer, and in a still another embodiment is a styrenic blockcopolymer. The spring (600) has a hardness in the range of 15-45 on aShore A hardness scale in an embodiment, and 20-40 on a Shore A hardnessscale in another embodiment, and 25-35 on a Shore A hardness scale instill a further embodiment.

In still another embodiment at least one of the following components areformed of a nonmetallic material: the clip (300), the support ring(500), the spring (600), the prong ring (700), the retainer latch (800),and the top insert (900); and in another embodiment the nonmetallicmaterial has a density of less than 2 g/cc and one, or more, of thefollowing properties: a ASTM D638 tensile strength of at least 30 Ksi at160° F., a ASTM D638 tensile modulus of at least 3500 Ksi at 160° F., aASTM D695 compressive strength of at least 33 Ksi at 160° F., a ASTMD695 compression modulus of at least 1000 Ksi at 160° F., a ASTM D6272flexural strength of at least 42 Ksi at 160° F., a ASTM D6272 flexuralmodulus of at least 2800 Ksi at 160° F., a ASTM D5379 shear strength ofat least 11 Ksi at 160° F., and a ASTM D5961 bearing strength of atleast 36 Ksi at 160° F. In a further embodiment the nonmetallic materialhas a density of less than 1.80 g/cc, and less than 1.60 g/cc, and lessthan 1.50 g/cc in additional embodiments. In one embodiment thenonmetallic material is a carbon fiber reinforced plastic material. Inone embodiment the strain relationships are achieved by having theprimary portion 10000 formed of a polyamide resin, while in a furtherembodiment the polyamide resin includes fiber reinforcement, and in yetanother embodiment the polyamide resin includes at least 35% fiberreinforcement. In one such embodiment the fiber reinforcement includeslong-glass fibers having a length of at least 10 millimeters pre-moldingand produce a finished primary portion 10000 having fiber lengths of atleast 3 millimeters, while another embodiment includes fiberreinforcement having short-glass fibers with a length of at least0.5-2.0 millimeters pre-molding. Incorporation of the fiberreinforcement increases the tensile strength of the primary portion10000, however it may also reduce the primary portion elongation tobreak therefore a careful balance must be struck to maintain sufficientelongation. Therefore, one embodiment includes 35-55% long fiberreinforcement, while in an even further embodiment has 40-50% long fiberreinforcement. One specific example is a long-glass fiber reinforcedpolyamide 66 compound with 40% carbon fiber reinforcement, such as theXuanWu XW5801 resin having a tensile strength of 245 megapascal and 7%elongation at break. Long fiber reinforced polyamides, and the resultingmelt properties, produce a more isotropic material than that of shortfiber reinforced polyamides, primarily due to the three-dimensionalnetwork formed by the long fibers developed during injection molding.Another advantage of long-fiber material is the almost linear behaviorthrough to fracture resulting in less deformation at higher stresses.

Additionally, the relative length, width, thickness, geometry, andmaterial properties of various components, and their relationships toone another and the other design variables disclosed herein, influencethe durability, ease of use, security, and safety of the fastener toachieve the goals. Now to put the disclosed ranges and relationshipsinto perspective with an embodiment of the fastener directed toaerospace applications where size, weight, and durability are essential,in an embodiment the BBPS width (476) is no more than 20 mm, and no morethan 15 mm, and no more than 10 mm in further embodiments. Similarly, inanother embodiment the BBPS length (478) is no more than 20 mm, and nomore than 15 mm, and no more than 10 mm in further embodiments.Likewise, in another embodiment the base plate length (440) is no morethan 10 mm, and no more than 7.5 mm, and no more than 5 mm in furtherembodiments. In a further embodiment the pillar lobe first radius (276)and the pillar lobe second radius (278) are no more than 10.0 mm, and nomore than 8.0 mm, and no more than 7.0 mm in further embodiments.However another series of embodiments caps this range and the pillarlobe first radius (276) and the pillar lobe second radius (278) are atleast 0.25 mm, and at least 0.35 mm, and at least 0.40 mm in furtherembodiments. Likewise, in another embodiment the base plate length (440)is no more than 10 mm, and no more than 7.5 mm, and no more than 5 mm infurther embodiments. In a further embodiment the BPPLER first radius(466) and the BPPLER second radius (468) are no more than 10.0 mm, andno more than 8.0 mm, and no more than 7.0 mm in further embodiments.However another series of embodiments caps this range and the BPPLERfirst radius (466) and the BPPLER second radius (468) are at least 0.25mm, and at least 0.35 mm, and at least 0.40 mm in further embodiments.In still a further embodiment the base plate bore width (452) is no morethan 15.0 mm, and no more than 12.5 mm, and no more than 10.0 mm infurther embodiments. In even further embodiments the pillar bore width(234) is no more than 10 mm, and no more than 8 mm, and no more than 6mm in further embodiments. The spring length (650) is no more than 12 mmin one embodiment, and no more than 10 mm, and no more than 8 mm infurther embodiments. Further, in one embodiment the top insert width(930) is no more than 22 mm, and no more than 20 mm, no more than 18, nomore than 16, and no more than 14 mm in further embodiments. In oneembodiment the spring length (650) is no more than 25.4 mm, and no morethan 20 mm, 15 mm, 10 mm, and 8 mm in further embodiments. In anotherembodiment, the spring maximum sidewall thickness is no more than 4.0mm, and no more than 3.0 mm, 2.5 mm, and 2.0 mm in further embodiments.

In one embodiment the insert pillar (200), the base plate (400), and/orthe base plate foundation (470) are formed of metallic material and thedensity is no more than 8 g/cc, and no more than 6.8 g/cc in anotherembodiment, and no more than 4.8 g/cc in a further embodiment, and nomore than 2.8 g/cc in still another embodiment. In another embodimentthe metallic material has an elongation to break of at least 5%, atleast 7%, 9%, 11%, 13%, and 14.5% in additional embodiments. Thenecessary strain and elongation requirements for durability must bebalanced with the need for strength and durability in the connection.Traditional design practices of simply designing the components to be asstrong as possible does not provide the needed durability of the blindfastener. In another embodiment the ultimate tensile strength is 754 and960 MPa, and in another embodiment the melting point is less than 1350degrees Celsius, while in a further embodiment the coefficient ofthermal expansion is no more than 14 (10⁻⁶/° C.), and the Young'sModulus is no more than 90 GPa in another embodiment, and the UltimateTensile Strength is no more than 1600 MPa in yet a further embodiment,and the Yield Strength is less than 150 MPa in still another embodiment.The metallic material may be a superelastic material in one embodiment,which may include a NiTi or Ni—Ti—Cu alloy system, Copper-Zinc-Aluminum(CuZnAl) alloy system, Fe—Mn—Si and Fe—Ni—Co—Ti alloy systems, andFe—Ni—Al alloy systems. In another embodiment the metallic material is ahigh strength stainless steel alloy with a minimum tensile strength of270 Ksi, and in a further embodiment no more than 300 Ksi.

Superelastic behavior of Nitinol is usually characterized through cyclictensile testing per ASTM F2516. A typical cyclic tensile curve forsuperelastic Nitinol can be broken into several different segments.During initial loading the austenite phase exhibits typical elasticdeformation up until the Upper Plateau Stress (UPS) is reached. Once theUPS has been reached an isostress condition is observed as the cubicaustenite structure shears into detwinned stress induced martensite(SIM), followed by the elastic deformation of the detwinned SIMstructure. Just as for the thermally induced phase transformation, theformation of SIM is reversible. During unloading elastic strain isrecovered and the SIM transforms back into the parent austenite phase.The recovery stress (or Lower Plateau Stress, LPS) is lower than UPS.The hysteresis observed arises from internal friction and defects in thecrystal structure. In one embodiment the expansion device (500) exhibitssuperelasticity up to at least 8% strain before permanent deformationbegins. In another embodiment the Upper Plateau Stress (UPS) is at least600 MPa, while in a further embodiment the Lower Plateau Stress (LPS) isat least 375 MPa, The lower plateau strength/stress (LPS) is the stressmeasured at 2.5% strain during tensile unloading of the sample, afterloading to 6% strain per the method described in ASTM F2516.Superelasticity is defined as nonlinear recoverable deformation behaviorof the shape memory alloys that occurs at temperatures above Af butbelow Md, where the austenite finish temperature (Af) is the temperatureat which martensite (or R-phase) to austenite, and martensitedeformation temperature (Md) is the highest temperature at whichmartensite will form from the austenite phase in response to an appliedstress. At temperature above Md the shape memory alloy will not exhibitsuperelasticity it will rather exhibit a typical elastic-plasticbehavior when loaded. In one embodiment the temperature in whichaustenite is complete is between −20° C. to −10° C., and provides a %elongation of at least 10% and an ultimate tensile strength of at least1250 MPa.

In a still further embodiment the top insert (900) is formed of anonmetallic material having a density of less than 2 g/cc and anelongation to break of at least 3% in one embodiment, and at least 4%,5%, 6%, 7%, and 8% in further embodiments. In a further embodiment thenonmetallic material has a density of less than 1.80 g/cc, and less than1.60 g/cc, and less than 1.40 g/cc, and less than 1.2 g/cc in additionalembodiments. In an embodiment the nonmetallic material is athermoplastic material, and a Polyetherimide (PEI) in a furtherembodiment, and, in still more embodiments, any of the followingmaterials that meet the claimed mechanical properties: polycaprolactam,a polyhexamethylene adipinamide, or a copolymer of hexamethylene diamineadipic acid and caprolactam, however other embodiments may includepolypropylene (PP), nylon 6 (polyamide 6), polybutylene terephthalates(PBT), thermoplastic polyurethane (TPU), PC/ABS alloy, PPS, PEEK, andsemi-crystalline engineering resin systems that meet the claimedmechanical properties. In one embodiment the nonmetallic material hasone, or more, of the following properties: a tensile strength of atleast 20 Ksi, a tensile modulus of at least 1000 Ksi, a flexuralstrength of at least 30 Ksi, a flexural modulus of at least 900 Ksi, acompressive strength of at least 20 Ksi, a compressive modulus of atleast 450 Ksi, a shear strength of at least 13 Ksi, and a Rockwell Mscale hardness of at least 105.

In still another embodiment at least one of the following metallic areformed of a metallic material with a density of less than 4.6 g/cc inone embodiment, and less than 3 g/cc in yet another embodiment; and inanother embodiment the material has one, or more, of the followingproperties: an ultimate tensile strength of at least 68 Ksi, and atleast 80 Ksi in anther embodiment; a tensile yield strength of at least47 Ksi, and at least 70 Ksi in another embodiment; an elongation tobreak of at least 9% in one embodiment, and at least 11% in anotherembodiment, and at least 13%, 15%, 17%, and 19% in still furtherembodiments; and/or a modulus of elasticity of at least 9000 Ksi in oneembodiment, and at least 10000 Ksi in another embodiment.

Some examples of metal alloys that can be used to form the components ofthe fastener (100) include, without limitation, magnesium alloys,aluminum/aluminum alloys (e.g., 3000 series alloys, 5000 series alloys,6000 series alloys, such as 6061-T6, and 7000 series alloys, such as7075, just to name a few), titanium alloys (e.g., 3-2.5, 6-4, SP700,15-3-3-3, 10-2-3, and other alpha/near alpha, alpha-beta, and beta/nearbeta titanium alloys, just to name a few), carbon steels (e.g., 1020 and8620 carbon steel, just to name a few), stainless steels (e.g., A286,301, 302, 303, 304 and 410 stainless steel), PH(precipitation-hardenable) alloys (e.g., 17-4, C450, and C455 alloys,just to name a few), copper alloys, and nickel alloys.

Another embodiment tunes the galvanic compatibility of the components ofthe blind fastener, along with the previously disclosed balancing ofrelationships, to provide preferential galvanic compatibility. Thus, inone embodiment there is no more than a 0.50 V difference in the “AnodicIndex” between any two of the components that come in contact with oneanother, while in another embodiment there is no more than a 0.25 Vdifference in the “Anodic Index” between any two of the components thatcome in contact with one another, and in yet another embodiment there isno more than a 0.15 V difference in the “Anodic Index” between any twoof the components that come in contact with one another; per thegalvanic data from MIL-STD-889.

In addition to the desired durability, reliability, and ease of use, thepredetermined movement/deflection of certain components, also known asthe goals, provided by the present fastener designs are provided by adelicate interplay of relationships of the various components, variableswithin each component as well as relationships across the components.The disclosed relationships are more than mere optimization,maximization, or minimization of a single characteristic or variable,and are often contrary to conventional design thinking, yet have beenfound to achieve a unique balance of the trade-offs associated withcompeting criteria such as durability, stress distribution, vibrationand fatigue resistance, weight, and ease of use. It is important torecognize that all the associated disclosure and relationships applyequally to all embodiments and should not be interpreted as beinglimited to the particular embodiment being discussed when a relationshipis mentioned. Further, the aforementioned balances require trade-offsamong the competing characteristics recognizing key points ofdiminishing returns, as often disclosed with respect to open and closedranges for particular variables and relationships. Proper functioning ofeach component, and the overall fastener, on each and every engagementcan be a matter of life or death. Therefore, this disclosure contains aunique combination of components and relationships that producereliable, consistent, and uniform deformation or deflection, that isadverse to fatigue and stress concentration failures, so that thefastener properly engages the panel (P) and provides a secure, yetadjustable, interface to secure additional components. While therelationships of the various features and dimensions of a singlecomponent play an essential role in achieving the goals, therelationships of features across multiple components are just ascritical, if not more critical, to achieving the goals.

With respect to the goal of achieving dependable predeterminedmovement/deflection of multiple individual components, interrelations ofthe multiple elements is critical to achieve a predetermined RLPdisplacement and/or a predetermined TILP displacement, as will now bediscussed in detail. As previously disclosed, in an uninstalled statethe RLP proximal ends (842) of the retainer latch projections (RLP)(840) extend beyond the retainer latch ring width (836), as seen in FIG.35 . Then, during installation as the fastener (100) is being pressed inthe panel aperture (PA), the plurality of retainer latch projections(840) deflect toward the longitudinal axis as they pass through thepanel (P) skin. Once the plurality of retainer latch projections (840)clear the panel (P) skin they spring back to their initial state withthe RLP proximal ends (842) located beneath the panel (P) skin, therebylocking the fastener within the panel aperture (PA). Each RLP proximalend (842) is designed to achieve a predetermined RLP displacementmeasured in the plane of the paper in FIG. 35 . Thus a maximum distancefrom the natural position of an undeflected RPL proximal end (842) tothe same located 180 degrees on the other side in FIG. 35 is equal tothe retainer latch ring width (836) plus twice the predetermineddisplacement.

Similarly, with respect to the top insert (900), seen in FIGS. 40, 69,70, 96, and 97 , it has a top insert width (930) that changes duringinstallation, and is designed to be larger than the panel aperture (PA).Like the plurality of retainer latch projections (840), the plurality oftop insert latching projections (960) flex towards the center of thefastener (100) during installation in the panel aperture (PA), causingthe top insert width (930) to decrease. Once the fastener (100) has beenpressed into its final position the plurality of top insert latchingprojections (960) spring outwards once they clear the panel (P) skinsurrounding the panel aperture (PA); thereby locking the fastener (100)in place. Further, the plurality of top insert latching projections(960) that are not located at the top insert proximal end (910), such asthose shown at the top insert distal end (920) don't need to flex, ordeflect, as they pass into the panel aperture (PA), but may, rather theyflex, or deflect, after the base plate foundation (480) has contact theopposite panel skin and the top insert (900) is forced toward the baseplate foundation (480), thereby causing these top insert latchingprojections (960) to then deflect outward as the spring (600) iscompressed, however they may flex, or deflect, as they pass into thepanel aperture (PA) as would be understood by the embodimentsillustrated in FIGS. 68 and 95 with their sloped end surfaces whichguide them inward as the sloped end surface contact the narroweraperture opening.

Nonetheless, the disclosed predetermined TILP displacement appliesregardless of if located at the top insert proximal end (910), the topinsert distal end (920), or somewhere in between.

Thus, just as each RLP proximal end (842) is designed to achieve apredetermined RLP displacement measured in the plane of the paper inFIG. 35 , each top insert latching projections (960) is designed toachieve a predetermined TILP displacement measured in the plane of thepaper in FIGS. 40, 69, 70, 96, and 97 . Therefore, the top insert width(930) is capable of changing from a maximum undeflected top insert widthto a minimum deflected top insert width during installation, where theminimum deflected top insert is equal to the maximum undeflected topinsert width minus two times the predetermined TILP displacement. Asseen in FIGS. 69, 70, 96, and 97 , the top insert latching projections(960) to not need to align 180 degrees apart, yet the maximumundeflected top insert width and the minimum deflected top insert widthcan be easily measured by one skilled in the art. Having multipleindividual elements achieving the predetermined displacements increasesthe reliability and safety of the fastener (100), thus in one embodimentthere are at least two individual deflectable elements, namely retainerlatch projections (840) and/or top insert latching projections (960),and at least three in another embodiment, and at least, four, five, six,seven, eight, nine, or ten, or more, in additional embodiments. Anotherseries of embodiments recognizes the diminishing returns and caps thenumber of individual deflectable elements to no more than 20 in oneembodiment, no more than 15 in another embodiment, no more than 10 instill a further embodiment, and no more than 8 in a final embodiment.

In one embodiment the predetermined RLP displacement and/orpredetermined TILP displacement is at least 0.25 mm, while in anotherembodiment they are at least 0.35 mm, and in a further embodiment theyare at least 0.45 mm. A further series of embodiments recognizesnegative consequences associated with trying to maximize thepredetermined displacements and therefore caps the predetermined RLPdisplacement and/or predetermined TILP displacement to no more than 2.00mm, and no more than 1.50 mm, 1.25 mm, 1.00 mm, and 0.75 mm in furtherembodiments.

The present designs may include a helical thread insert, as seen in FIG.99 , as disclosed in U.S. patent application Ser. Nos. 17/395,074,15/595,620, and 15/906,549, as well as any of the design features anddisclosure in U.S. patent application Ser. Nos. 17/379,488, 17/317,314,which are hereby fully incorporated by reference. The helical threadinsert may include a locking thread, which is non-circular and differsfrom the other threads, and in FIG. 99 is illustrated approximately atthe midpoint of the pillar bore length (236). However, in a furtherembodiment the locking thread is located between the midpoint of thepillar bore length (236) and the end of the end of the insert pillar(200) that received an external fastener threaded into the pillar bore(230). In fact in a further embodiment the locking thread is locatedfrom one of the ends of the insert pillar (200) a locking threaddistance that is no more than 45% of the pillar bore length (236), andno more than 40% in another embodiment, and no more than 35% in still afurther embodiment. However, another series of embodiments introduces afloor on this range with the locking thread distance being at least 20%of the pillar bore length (236), and at least 25%, and 30% in furtherembodiments.

The previously described adhesive on the base plate foundation (480),the base plate distal end (420), and/or pillar distal end (220) is apressure sensitive adhesive in one embodiment. In a further embodimentthe pressure sensitive adhesive is in tape form with an external releaselayer, while in a further embodiment it is thermally activated and/or UVactivated. In one embodiment the pressure sensitive adhesive isthermally activated at a temperature of at least 150° F. for anactivation period, and at least 200° F. for the activation period inanother embodiment, and at least 250° F., and 275° F. in still furtherembodiments. In one embodiment the activation period is at least 5minutes, and at least 7.5 minutes, 10 minutes, 12.5 minutes, and 15minutes in further embodiments. Additional embodiments cap these ranges.For example in one embodiment the activation temperature is no more than500° F., and no more than 450° F., and 400° F. in further embodiments.In another embodiment the activation period is no more than 30 minutes,and no more than 25 minutes, and 20 minutes in additional embodiments.The heat may be applied externally to the skin of the panel and/ordirectly to a component, or components, of the fastener (100) via aninduction coil. For instance, in one embodiment, using the embodiment ofFIG. 47 for reference, the insert pillar (200), the base plate (400),and the base plate foundation (480), in those embodiments having a baseplate foundation (480) are first inserted in the panel aperture, then aninduction coil is inserted in the aperture surrounding a portion of thebase plate (400) and thereby heats the components to the activationtemperature for the activation period. Further, the induction coil toolmay engage the end of the base plate (400) and exert a longitudinalforce on the components throughout the activation period. Thelongitudinal force produces an activation pressure on the adhesive thatis at least 50 psi in one embodiment, at least 75 psi in anotherembodiment, and at least 100 psi in still a further embodiment. Afurther series of embodiments caps the activation pressure to controlthe spread of adhesive and reduce the potential for damaging the panel,thus in one such embodiment the activation pressure is no more than 250psi, and no more than 200 psi, and no more than 150 psi in furtherembodiments. In such induction coil embodiments incorporating anactivation pressure, the activation time is no more than 5 minutes inone embodiment, no more than 3 minutes in another embodiment, and nomore than 1 minute in still a further embodiment. Then, the insertpillar (200), the base plate (400), and the base plate foundation (480)are allowed to cool to a temperature of less than 150° F. and the spring(600) and top insert (900) are installed, and subsequently potted inplace in some embodiments. In one embodiment the pressure sensitiveadhesive is a transposable pressure sensitive adhesive that exhibitsproperties like a removable label at application, but transposes to ahigh-strength pressure sensitive adhesive in a second stage, whenactivated by an external stimuli such as the disclosed thermal and UVactivations. The activation may trigger a chemical reaction causing theadhesion properties to change after application. Whether the change inadhesion properties was to another PSA type or to structural wasdependent on the application. In these embodiments, the transpositionchemistry is epoxy polymerization via the activators. However, in someembodiments traditional pressure sensitive adhesives and structuraladhesives having only one activation (coating/drying PSAs or mixingtwo-part structural adhesives) are incorporated.

Numerous alterations, modifications, and variations of the embodimentsdisclosed herein will be apparent to those skilled in the art and theyare all anticipated and contemplated to be within the spirit and scopeof the instant invention. For example, although specific embodimentshave been described in detail, those with skill in the art willunderstand that the preceding embodiments and variations can be modifiedto incorporate various types of substitute and or additional oralternative materials, relative arrangement of elements, and dimensionalconfigurations. Accordingly, even though only few variations of thepresent invention are described herein, it is to be understood that thepractice of such additional modifications and variations and theequivalents thereof, are within the spirit and scope of the invention asdefined in the following claims.

We claim:
 1. A fastener (100) for attachment to a panel (P), having aninner skin and an outer skin, via a panel aperture (PA) in the outerskin, comprising: an insert pillar (200), a base plate (400), a spring(600), and a top insert (900); the insert pillar (200) having a pillarproximal end (210), a pillar distal end (220), a pillar bore (230)extending into the insert pillar (200) from the pillar proximal end(210) and defining a longitudinal axis of the fastener (100), and aplurality of pillar lobes (270) located adjacent the pillar distal end(220); the base plate (400) having a base plate proximal end (410), abase plate distal end (420), a base plate bore (450) that extends fromthe base plate proximal end (410) to the base plate distal end (420) andreceives at least a portion of the insert pillar (200), a base plateexterior surface, and a plurality of base plate pillar lobe engagementrecesses (460) that receive at least a portion of the plurality ofpillar lobes (270) and prevent the base plate (400) and insert pillar(200) from rotating relative to one another; the spring (600) in contactwith a portion of the base plate exterior surface and having a springproximal end (610), a spring distal end (620), a spring bore extendinginto the spring (600) from the spring distal end (620) and defining aspring internal surface, and a spring external surface having aplurality of spring slots (680), extending from the spring proximal end(610) toward the spring distal end (620), and a plurality of spring TILPactivation features (490), wherein each spring slot (680) has a springslot width (682), a spring slot length (684), and a spring slot depth(686); the top insert (900) having a top insert proximal end (910) witha top insert opening providing access to the pillar bore (230), a topinsert distal end (920), a plurality of top insert latching projections(960) adjacent the top insert proximal end (910), a plurality of offsetlatching projections positioned to cooperate with the plurality ofspring TILP activation features (490), and a top inert interior surfacein contact with a portion of the spring (600); wherein in an uninstalledstate the top insert latching projections (960) are deflectable inwardfrom a first radial position toward the longitudinal axis, through apredetermined TILP displacement, to a second radial position, so thatthe fastener (100) passes through the panel aperture (PA) and the topinsert latching projections (960) automatically return to the firstposition and engage the panel outer skin; wherein in the uninstalledstate the spring (600) establishes a first stand-off distance betweenthe top insert proximal end (910) and the base plate distal end (420),and in an installed state a portion of the spring (600) is compressed inthe direction of the longitudinal axis by application of a longitudinalforce against the top insert (900) with a fastener distal end (120)restrained by the panel inner skin, thereby reducing the first stand-offdistance to a second stand-off distance between the top insert proximalend (910) and the base plate distal end (420); and wherein thelongitudinal compression of the spring (600) produces radial expansionof a portion of the spring (600) and the spring TILP activation features(490), causing deflection of at least one of the offset latchingprojections outward away from the longitudinal axis.
 2. The fastener(100) of claim 1, wherein each offset latching projection is angularlyoffset at least 10 degrees from the adjacent top insert latchingprojections (960).
 3. The fastener (100) of claim 2, wherein at leastone spring slot (680) is located between each top insert latchingprojections (960) and the nearest offset latching projections.
 4. Thefastener (100) of claim 2, wherein the plurality of top insert latchingprojections (960) includes 3-20 top insert latching projections (960),and the plurality of pillar lobes (270) includes 3-24 pillar lobes(270).
 5. The fastener (100) of claim 1, wherein the spring slot width(682) is at least 75% of the spring slot depth (686), and the springslot length (684) is greater than the spring slot width (682) and thespring slot depth (686).
 6. The fastener (100) of claim 5, wherein thespring slot length (684) is no more than 12 times greater than thespring slot width (682), the spring slot width (682) is no more than300% of the spring slot depth (686), and a spring sidewall thickness isno more than 4 mm.
 7. The fastener (100) of claim 1, wherein the spring(600) is formed of an elastomeric material having a spring hardness of15-45 on a Shore A hardness scale.
 8. The fastener (100) of claim 7,wherein the spring (600) creates a friction fit between a portion of thebase plate (400), a portion of the spring (600), and a portion of thetop insert (900).
 9. The fastener (100) of claim 8, wherein the spring(600) is a unitary piece of material that encircles a portion of thebase plate (400).
 10. The fastener (100) of claim 9, wherein in theuninstalled state the spring (600) has a spring length measured parallelto the longitudinal axis between the spring proximal end (610) and thespring distal end (620), and the spring length is within 40% of a baseplate pillar shroud length (478).
 11. The fastener (100) of claim 10,wherein the spring length is no more than 12 mm, and the predeterminedTILP displacement is 0.25-2.00 mm.
 12. The fastener (100) of claim 7,wherein the top insert (900) is formed of nonmetallic material having adensity of less than 2 g/cc.
 13. The fastener (100) of claim 12, whereinthe top insert (900) has a hardness of 100-150 on a Rockwell R scale.14. The fastener (100) of claim 12, wherein the insert pillar (200) isformed of metallic material having a density of no more than 8 g/cc. 15.The fastener (100) of claim 7, wherein a difference between the firststand-off distance and the second stand-off distance is 0.5-5.0 mm whenthe longitudinal force is 5-50 lbf.
 16. The fastener (100) of claim 15,wherein in the installed state the spring (600) biases the top insert(900) away from the base plate (400) and produces a biasing pressure onthe top insert (900) of at least 5 psi.
 17. The fastener (100) of claim15, wherein a portion of the top insert (900) engages the springproximal end (610) so that the longitudinal compression of the spring(600) causes the spring proximal end (610) to deflect inward at least0.3 mm toward the longitudinal axis and cover a portion of the baseplate proximal end (410), when the longitudinal force is 5-50 lbf.
 18. Afastener (100) for attachment to a panel (P), having an inner skin andan outer skin, via a panel aperture (PA) in the outer skin, comprising:an insert pillar (200), a base plate (400), a spring (600), and a topinsert (900); the insert pillar (200) having a pillar proximal end(210), a pillar distal end (220), a pillar bore (230) extending into theinsert pillar (200) from the pillar proximal end (210) and defining alongitudinal axis of the fastener (100), and a plurality of pillar lobes(270) located adjacent the pillar distal end (220); the base plate (400)having a base plate proximal end (410), a base plate distal end (420), abase plate bore (450) that extends from the base plate proximal end(410) to the base plate distal end (420) and receives at least a portionof the insert pillar (200), a base plate exterior surface, and aplurality of base plate pillar lobe engagement recesses (460) thatreceive at least a portion of the plurality of pillar lobes (270) andprevent the base plate (400) and insert pillar (200) from rotatingrelative to one another; the spring (600) in contact with a portion ofthe base plate exterior surface and having a spring proximal end (610),a spring distal end (620), a spring bore extending into the spring (600)from the spring distal end (620) and defining a spring internal surface,and a spring external surface having a plurality of spring slots (680),extending from the spring proximal end (610) toward the spring distalend (620), wherein each spring slot (680) has a spring slot width (682),a spring slot length (684), and a spring slot depth (686), and whereinthe spring (600) is formed of an elastomeric material having a springhardness of 15-45 on a Shore A hardness scale; the top insert (900)having a top insert proximal end (910) with a top insert openingproviding access to the pillar bore (230), a top insert distal end(920), a plurality of top insert latching projections (960) adjacent thetop insert proximal end (910), and a top inert interior surface incontact with a portion of the spring (600), wherein the top insert (900)is formed of nonmetallic material having a density of less than 2 g/cc;wherein in an uninstalled state the top insert latching projections(960) are deflectable inward from a first radial position toward thelongitudinal axis, through a predetermined TILP displacement, to asecond radial position, so that the fastener (100) passes through thepanel aperture (PA) and the top insert latching projections (960)automatically return to the first position and engage the panel outerskin; and wherein in the uninstalled state the spring (600) establishesa first stand-off distance between the top insert proximal end (910) andthe base plate distal end (420), and in an installed state a portion ofthe spring (600) is compressed in the direction of the longitudinal axisby application of a longitudinal force against the top insert (900) witha fastener distal end (120) restrained by the panel inner skin, therebyreducing the first stand-off distance to a second stand-off distancebetween the top insert proximal end (910) and the base plate distal end(420), and a difference between the first stand-off distance and thesecond stand-off distance is 0.5-5.0 mm when the longitudinal force is5-50 lbf.; and wherein at least one spring slot (680) is located betweeneach top insert latching projections (960), the plurality of top insertlatching projections (960) includes 3-20 top insert latching projections(960), the plurality of pillar lobes (270) includes 3-24 pillar lobes(270), the spring slot width (682) is at least 75% of the spring slotdepth (686), and the spring slot length (684) is greater than the springslot width (682) and the spring slot depth (686).
 19. The fastener (100)of claim 18, wherein in the installed state the spring (600) biases thetop insert (900) away from the base plate (400) and produces a biasingpressure on the top insert (900) of at least 5 psi.
 20. The fastener(100) of claim 18, wherein a portion of the top insert (900) engages thespring proximal end (610) so that the longitudinal compression of thespring (600) causes the spring proximal end (610) to deflect inward atleast 0.3 mm toward the longitudinal axis and cover a portion of thebase plate proximal end (410), when the longitudinal force is 5-50 lbf.